3 ms·
If you could play God and place blobs of dark matter in the right places and moving at the right speeds, it seems plausible that such a dark matter Galaxy could
by ohazi 8y ago
If you could play God and place blobs of dark matter in the right places and moving at the right speeds, it seems plausible that such a dark matter Galaxy could physically exist and be stable.
But I don't think we know of a mechanism for such a structure to form naturally. Normal particles collide and transform some of their gravitational energy into heat. If dark matter only interacts gravitationally, blobs of it would pass right through each other without losing energy. I think(?) you need these sorts of collisional energy losses to get matter to coalesce into a galaxy.
- Retric 8y agoYou can get the equivalent of evaporative cooling in an unstable multi body system. You occasionally kick out an object which takes more energy away than the average body that remains. The formation of a dark matter galaxy in such a fashion is plausible, but would take a long time.
- marcosdumay 8y agoThat require that the bodies exchange energy to get near the lower average, and transfer some energy to a few hot particles. Otherwise, you won't get any cooling.
- stcredzero 8y agoThat could be done entirely through gravitational mechanisms. There's something like that which happens to globular clusters.
- selimthegrim 8y agoYou might be interested in Lynden-Bell’s papers
- stcredzero 8y agoThanks. I'm just going by a tidbit from DeepSkyVideos on YouTube. They specifically mention a similarity to evaporative cooling. I just found the video! ("Gravothermal Catastrophe") https://www.youtube.com/watch?v=LYnoV2n5ptg https://www.youtube.com/watch?v=LYnoV2n5ptg
- ncmncm 8y agoAre you aware of the concept of Dynamical Friction? There is nothing speculative about it. It slows down objects above the average speed by ordinary Newton-style gravitational interactions.